The present invention relates to a lens-position controller and an imaging module, and relates more specifically to an imaging module in which an image sensor having a light receiving portion, and a lens for imaging an incident light in the light receiving portion are modularized (integrated), and a lens-position controller for controlling a position of the lens with respect to the light receiving portion in the imaging module.
An image sensor, such as a CCD, a CMOS imager, or the like, which is a kind of a semi-conductor, is used in various fields. Particularly, a camera mobile phone to which camera functions are added, in addition to communication functions, by incorporating the image sensor is widely put into practical use. With a reduction in size, thickness, and weight of a product itself, such as a camera mobile phone, a digital camera, or the like, an imaging module in which an image sensor and a lens are modularized has come into practical use.
In a recent imaging module, an imaging module incorporating an automatic focusing adjustment (autofocus) mechanism capable of providing clear images by moving a position of a lens to thereby automatically adjust an optical path length of the lens into a focal distance, has come into practical use. Utilizing such an autofocus mechanism makes it possible to dynamically change the focal distance according to a distance of a subject to thereby address broad requests even when the lens itself does not have a high performance.
Meanwhile, when a lens and a lens barrel are manufactured, there may arise a focus gap resulting from respective manufacturing variabilities, but incorporating the autofocus mechanism can eliminate the need of adjusting a focus at the time of factory shipment, so that the autofocus mechanism results in very effective means also for manufacturers.
Incidentally, a conventional autofocus mechanism mainly employs a mechanical drive system, and a present situation is that the structure becomes complicated and the weight is increased. Meanwhile, in recent years, artistic aspects, such as a color tone of the image, clearness of the image due to a depth of field, or the like, have become important, and for this reason, a mechanism in which a number of lenses are combined has come into practical use. In this case, focal distances of respective lenses have needed to be adjusted, thus resulting in further contributing to an increase in structure and weight of the mechanism.
In Japanese Patent Application Laid-Open No. 2004-251999, there is disclosed an AF drive mechanism of a camera provided with a motor, at least a part the motor being arranged at the bottom in a camera body, and a rotatable shaft of the motor being positioned in a direction perpendicular to an optical axis of a lens barrel which is provided in the camera body, a worm-gear integrally formed in the rotatable shaft, a first cylindrical material in which a wheel gear engaging with the worm-gear is formed in an outer peripheral surface, an AF coupler having a joint portion with the lens barrel, a second cylindrical material for supporting the AF coupler, a connecting material for connecting between the first cylindrical material and the second cylindrical material, wherein the AF drive mechanism is arranged in a space formed with a part of a circular edge portion of a lens mount in which the lens barrel is provided, and a tangent of a point closest to the bottom of the camera body in the edge portion of the lens mount.
In Japanese Patent Application Laid-Open No. 2004-280031, there is disclosed a lens driving device provided with a cylindrical yoke with U shape, a magnet attached to an inner surface of an outside wall of the yoke, a carrier having a lens in the center, a coil mounted on the carrier, a base equipped with the yoke, a frame for supporting the base, two springs for supporting the carrier, wherein the two springs being the same part are arranged so as to support both sides of the carrier from the upper and lower sides, and each of the springs is operated as a power feeding path to the coil, so that a moving distance of the lens that is mounted on the carrier is controlled by a balance between a current value applied to the coil and stability of the two springs.
In Japanese Patent Application Laid-Open No. S58-86512 (1983), there is disclosed a focusing mechanism provided with a cylinder room arranged along an axial direction at an end point of an endoscope, and openings of both ends of the cylinder room being hermetically sealed with a transparent material, a lens frame movably hermetically fitted in the cylinder room in the axial direction while holding at least a part of the objective lens system, and supply-and-exhaustion paths respectively arranged in two rooms of the cylinder room which are divided by the lens frame, wherein the lens frame is moved by supplying and draining a transparent fluid to and from the two rooms via the supply-and-exhaustion paths to thereby perform focusing.